Qualitative and especially quantitative antigens and antibody measurements are of importance in clinical chemistry, physiology, and modern biotechnology. There exists an expanding interest in developing convenient sensitive nonisotopic labeled immunoassays. Among these, immunoassays appear to be oractical. In most such assays ultimate measurement is by optical methods.
Electrochemical determination offers two practical advantages:
1. They use relatively inexpensive and simple instruments. PA1 2. They are capable of making measurements even in highly turbid systems.
Considerable efforts have been made to develop membrane electrode sensors for antigen and antibody measurements. Antibodies were immobilized on gelatin membranes which were attached to an oxygen electrode. In such devices specific antibodies are immobilized onto a membrane and are applied in a solid phase "sandwich" procedure.
According to the invention described herein the antibodies or antigens are bound directly to an electrically conductive electrode. Together with an amperometric or other electro-chemical system, high sensitivity and reproducibility of measurements of antigens and antibodies, respectively, can be obtained.
The determination of LDH5 (which is part of the entire LDH content) in sera is of clinical significance as the level of LDH5 is indicative of liver functions, an increased content indicating liver malfunction. In a similar manner LDH1 can be determined, and this is of value in tests for coronary infarcts and the like.